The DCCT is a clinical study
conducted from 1983 to 1993 by the National Institute of
Diabetes and Digestive and Kidney Diseases (NIDDK). The study
showed that keeping blood sugar levels as close to normal as
possible slows the onset and progression of eye, kidney, and
nerve diseases caused by diabetes. In fact, it demonstrated that
any sustained lowering of blood sugar helps, even if the person
has a history of poor control.

The largest, most comprehensive diabetes study ever conducted,
the DCCT involved 1,441 volunteers with insulin-dependent
diabetes mellitus (IDDM) and 29 medical centers in the United
States and Canada. Volunteers had diabetes for at least 1 year
but no longer than 15 years. They also were required to have no,
or only early signs of, diabetic eye disease.

The study compared the effects of two treatment
regimens--standard therapy and intensive control--on the
complications of diabetes. Volunteers were randomly assigned to
each treatment group.

All DCCT participants were
monitored for diabetic retinopathy, an eye disease that affects
the retina. Study results showed that intensive therapy reduced
the risk for developing retinopathy by 76 percent. In
participants with some eye damage at the beginning of the study,
intensive management slowed the progression of the disease by 54
percent.

The retina is the light sensing tissue at the back of the eye.
According to the National Eye Institute, one of the National
Institutes of Health, as many as 24,000 persons with diabetes
lose their sight each year. In the United States, diabetic
retinopathy is the leading cause of blindness in adults under
age 65.

Participants in the DCCT were
tested to assess the development of diabetic kidney disease
(nephropathy). Findings showed that intensive treatment
prevented the development and slowed the progression of diabetic
kidney disease by 50 percent.

Diabetic kidney disease is the most common cause of kidney
failure in the United States and the greatest threat to life in
adults with IDDM. After having diabetes for 15 years, one-third
of people with IDDM develop kidney disease. Diabetes damages the
small blood vessels in the kidneys, impairing their ability to
filter impurities from blood for excretion in the urine. Persons
with kidney damage must have a kidney transplant or rely on
dialysis to cleanse their blood.

Participants in the DCCT were
examined to detect the development of nerve damage (diabetic
neuropathy). Study results showed the risk of nerve damage was
reduced by 60 percent in persons on intensive treatment.

Diabetic nerve disease can cause pain and loss of feeling in
the feet, legs, and fingertips. It can also affect the parts of
the nervous system that control blood pressure, heart rate,
digestion, and sexual function. Neuropathy is a major
contributing factor in foot and leg amputations among people
with diabetes.

DCCT participants were not
expected to have many heart-related problems because their
average age was only 27 when the study began. Nevertheless, they
underwent cardiograms, blood pressure tests, and laboratory
tests of blood fat levels to look for signs of cardiovascular
disease. The study proved that volunteers on intensive treatment
had significantly lower risks of developing high cholesterol, a
cause of heart disease. The risk was 35 percent lower in these
volunteers, suggesting that intensive treatment can help prevent
heart disease.

In the DCCT, the most significant
side effect of intensive treatment was an increase in the risk
for low blood sugar episodes severe enough to require assistance
from another person. This is called severe hypoglycemia. Because
of this risk, DCCT researchers do not recommend intensive
therapy for children under age 13, people with heart disease or
advance complications, older adults, and people with a history
of frequent severe hypoglycemia. Persons in the intensive
management group also gained a modest amount of weight,
suggesting that intensive treatment may not be appropriate for
people with diabetes who are overweight.

DCCT researchers estimate that intensive management doubles the
cost of managing diabetes because of increased visits to health
care professional and the need for more frequent blood testing
at home. However, this cost is offset by the reduction in
medical expenses related to long-term complications and by the
improved quality of life of people with diabetes.

Results of the DCCT are reported
in the New England Journal of Medicine, 329(14),
September 30, 1993.

Other articles related to the DCCT will be published in various
journals during the next few years. For reprints of articles,
please write to:

National Diabetes Information Clearinghouse

The National Diabetes Information Clearinghouse (NDIC) is a
service of the National Institute of Diabetes and Digestive and
Kidney Diseases (NIDDK). The NIDDK is part of the National
Institutes of Health under the U.S. Public Health Service.
Established in 1978, the clearinghouse provides information
about diabetes to people with diabetes and their families,
health care professionals, and the public. NDIC answers
inquiries; develops, reviews, and distributes publications; and
works closely with professional and patient organizations and
government agencies to coordinate resources about diabetes.

Publications produced by the clearinghouse are reviewed
carefully for scientific accuracy, content, and readability.

This e-text is not copyrighted. The clearinghouse encourages
users of this e-pub to duplicate and distribute as many copies
as desired.

NIH Publication No. 94-3874
August 1994

e-text posted: 18 February 1998

Last Updated: Thursday February 27, 2014 19:28:21
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